On Thursday, National Guard troops will join emergency workers in order to find survivors, like Patti Perez. It took three men to pull her free after the storm left her trapped in her flattened home.

"I couldn't get up," she said. "I was having to move stuff off of me and got up and this is what I woke up to."

Another storm victim, Shameka Robinson, tried to find shelter in a gas station, but the storm destroyed it.

"The ceiling collapsed on me. The door slammed back on me. I was pinned against the wall," she said.

Even forecasters at the National Weather Service in Huntsville had to leave their building to find better cover.

West of Huntsville, the Browns Ferry Nuclear Power Plant lost power. Workers had to fire up gasoline-powered generators to keep the units safely running.

"Before it hit, there were branches falling out of the sky before we even knew the tornado was coming," storm survivor John Pitre recalled.

Meanwhile, in Smithville, Miss., nearly all of the town landmarks were destroyed by tornadoes. Residents had just moments to find protection from the storm.

"We grabbed a quilt and personal belongings and we went into the boardroom and got under the board table," Smithville Mayor Gregg Kennedy said. "When it was over, everything was gone."

Residents in Poplar Bluff, Mo., already barraged by catastrophic flooding, also had to contend with hail brought by the storms.

"Our hearts go out to all those who have been affected by this devastation, and we commend the heroic efforts of those who have been working tirelessly to respond to this disaster," President Obama said in a statement.

Meanwhile, the American Red Cross has activated half of its national chapters in response to the unprecedented death and destruction caused by the storms.